Hypertension is a chronic medical condition in which the blood pressure in the arteries is elevated. The high blood pressure implies that the heart of the patient needs to work harder than normal to maintain blood circulation throughout the body.
Persistent hypertension also has severe sequelae in the form of increased risk for stroke, myocardial infarction, heart failure, aortic aneurysm and chronic kidney disease.
A general approach in treating hypertension is a change of lifestyle, including dietary changes, physical exercise and weight loss. Medications in the form of antihypertensive drugs are also common, possible in the form of various combinations of different classes of antihypertensive agents, such as beta-blockers, calcium channel blockers (CCB), angiotensin converting enzyme inhibitors (ACE-I) and thiazide-based diuretic.
Another approach to combat hypertension is to use renal sympathetic nerve ablation, Schlaich et al., Renal sympathetic-nerve ablation for uncontrolled hypertension, The New England Journal of Medicine 361: 932-934, 2009 and Krum et al., Catheter-based renal sympathetic denervation for resistant hypertension: a multicentre safety and proof-of-concept study, Lancet 373: 1275-1281, 2009. The sympathetic nervous system plays an important role in circulatory and metabolic control and has been established as a major contributor to the development of hypertension since elevated sympathetic nerve activity initiates and sustains elevated blood pressure. Consequences of increased sympathetic activity to the kidneys include sodium and water retention, increased renin release and alteration of renal blood flow—effects that contribute to both acute and long-term blood pressure elevations. Hence, a catheter-based radio frequency (RF) ablation has been tested to excise renal nerves. RF ablation was applied to renal arteries using an ablation catheter with the beneficial effects of reduced renin activity, increased renal plasma flow and a progressive and sustained reduction in systemic blood pressure.
There is, though, a need for an improved control in the renal sympathetic nerve ablation procedure as compared to the prior art techniques requiring a manual maintenance of the ablation catheter in correct position, with the imminent risk of causing lesions at undesired parts of the renal artery and surrounding tissue.